import { md5Hash, newObjectId } from './cryptoUtils';
import { logger }               from './logger';
import rest                     from './rest';
import Auth                     from './Auth';

const PUSH_STATUS_COLLECTION = '_PushStatus';
const JOB_STATUS_COLLECTION = '_JobStatus';

const incrementOp = function(object = {}, key, amount = 1) {
  if (!object[key]) {
    object[key] = {__op: 'Increment', amount: amount}
  } else {
    object[key].amount += amount;
  }
  return object[key];
}

export function flatten(array) {
  var flattened = [];
  for(var i = 0; i < array.length; i++) {
    if(Array.isArray(array[i])) {
      flattened = flattened.concat(flatten(array[i]));
    } else {
      flattened.push(array[i]);
    }
  }
  return flattened;
}

function statusHandler(className, database) {
  let lastPromise = Promise.resolve();

  function create(object) {
    lastPromise = lastPromise.then(() => {
      return database.create(className, object).then(() => {
        return Promise.resolve(object);
      });
    });
    return lastPromise;
  }

  function update(where, object) {
    lastPromise = lastPromise.then(() => {
      return database.update(className, where, object);
    });
    return lastPromise;
  }

  return Object.freeze({
    create,
    update
  })
}

function restStatusHandler(className, config) {
  let lastPromise = Promise.resolve();
  const auth = Auth.master(config);
  function create(object) {
    lastPromise = lastPromise.then(() => {
      return rest.create(config, auth, className, object)
        .then(({ response }) => {
          // merge the objects
          return Promise.resolve(Object.assign({}, object, response));
        });
    });
    return lastPromise;
  }

  function update(where, object) {
    // TODO: when we have updateWhere, use that for proper interfacing
    lastPromise = lastPromise.then(() => {
      return rest.update(config, auth, className, { objectId: where.objectId }, object)
        .then(({ response }) => {
          // merge the objects
          return Promise.resolve(Object.assign({}, object, response));
        });
    });
    return lastPromise;
  }

  return Object.freeze({
    create,
    update
  })
}

export function jobStatusHandler(config) {
  let jobStatus;
  const objectId = newObjectId(config.objectIdSize);
  const database = config.database;
  const handler = statusHandler(JOB_STATUS_COLLECTION, database);
  const setRunning = function(jobName, params) {
    const now = new Date();
    jobStatus = {
      objectId,
      jobName,
      params,
      status: 'running',
      source: 'api',
      createdAt: now,
      // lockdown!
      ACL: {}
    }

    return handler.create(jobStatus);
  }

  const setMessage = function(message) {
    if (!message || typeof message !== 'string') {
      return Promise.resolve();
    }
    return handler.update({ objectId }, { message });
  }

  const setSucceeded = function(message) {
    return setFinalStatus('succeeded', message);
  }

  const setFailed = function(message) {
    return setFinalStatus('failed', message);
  }

  const setFinalStatus = function(status, message = undefined) {
    const finishedAt = new Date();
    const update = { status, finishedAt };
    if (message && typeof message === 'string') {
      update.message = message;
    }
    return handler.update({ objectId }, update);
  }

  return Object.freeze({
    setRunning,
    setSucceeded,
    setMessage,
    setFailed
  });
}

export function pushStatusHandler(config, existingObjectId) {

  let pushStatus;
  const database = config.database;
  const handler = restStatusHandler(PUSH_STATUS_COLLECTION, config);
  let objectId = existingObjectId;
  const setInitial = function(body = {}, where, options = {source: 'rest'}) {
    const now = new Date();
    let pushTime = now.toISOString();
    let status = 'pending';
    if (body.hasOwnProperty('push_time')) {
      if (config.hasPushScheduledSupport) {
        pushTime = body.push_time;
        status = 'scheduled';
      } else {
        logger.warn('Trying to schedule a push while server is not configured.');
        logger.warn('Push will be sent immediately');
      }
    }

    const data =  body.data || {};
    const payloadString = JSON.stringify(data);
    let pushHash;
    if (typeof data.alert === 'string') {
      pushHash = md5Hash(data.alert);
    } else if (typeof data.alert === 'object') {
      pushHash = md5Hash(JSON.stringify(data.alert));
    } else {
      pushHash = 'd41d8cd98f00b204e9800998ecf8427e';
    }
    const object = {
      pushTime,
      query: JSON.stringify(where),
      payload: payloadString,
      source: options.source,
      title: options.title,
      expiry: body.expiration_time,
      expiration_interval: body.expiration_interval,
      status: status,
      numSent: 0,
      pushHash,
      // lockdown!
      ACL: {}
    }
    return handler.create(object).then((result) => {
      objectId = result.objectId;
      pushStatus = {
        objectId
      };
      return Promise.resolve(pushStatus);
    });
  }

  const setRunning = function(batches) {
    logger.verbose(`_PushStatus ${objectId}: sending push to installations with %d batches`, batches);
    return handler.update(
      {
        status:"pending",
        objectId: objectId
      },
      {
        status: "running",
        count: batches
      }
    );
  }

  const trackSent = function(results, UTCOffset, cleanupInstallations = process.env.PARSE_SERVER_CLEANUP_INVALID_INSTALLATIONS) {
    const update = {
      numSent: 0,
      numFailed: 0
    };
    const devicesToRemove = [];
    if (Array.isArray(results)) {
      results = flatten(results);
      results.reduce((memo, result) => {
        // Cannot handle that
        if (!result || !result.device || !result.device.deviceType) {
          return memo;
        }
        const deviceType = result.device.deviceType;
        const key = result.transmitted ? `sentPerType.${deviceType}` : `failedPerType.${deviceType}`;
        memo[key] = incrementOp(memo, key);
        if (typeof UTCOffset !== 'undefined') {
          const offsetKey = result.transmitted ? `sentPerUTCOffset.${UTCOffset}` : `failedPerUTCOffset.${UTCOffset}`;
          memo[offsetKey] = incrementOp(memo, offsetKey);
        }
        if (result.transmitted) {
          memo.numSent++;
        } else {
          if (result && result.response && result.response.error && result.device && result.device.deviceToken) {
            const token = result.device.deviceToken;
            const error = result.response.error;
            // GCM errors
            if (error === 'NotRegistered' || error === 'InvalidRegistration') {
              devicesToRemove.push(token);
            }
            // APNS errors
            if (error === 'Unregistered' || error === 'BadDeviceToken') {
              devicesToRemove.push(token);
            }
          }
          memo.numFailed++;
        }
        return memo;
      }, update);
    }

    logger.verbose(`_PushStatus ${objectId}: sent push! %d success, %d failures`, update.numSent, update.numFailed);
    logger.verbose(`_PushStatus ${objectId}: needs cleanup`, { devicesToRemove });
    ['numSent', 'numFailed'].forEach((key) => {
      if (update[key] > 0) {
        update[key] = {
          __op: 'Increment',
          amount: update[key]
        };
      } else {
        delete update[key];
      }
    });

    if (devicesToRemove.length > 0 && cleanupInstallations) {
      logger.info(`Removing device tokens on ${devicesToRemove.length} _Installations`);
      database.update('_Installation', { deviceToken: { '$in': devicesToRemove }}, { deviceToken: {"__op": "Delete"} }, {
        acl: undefined,
        many: true
      });
    }

    // indicate this batch is complete
    incrementOp(update, 'count', -1);

    return handler.update({ objectId }, update).then((res) => {
      if (res && res.count === 0) {
        return this.complete();
      }
    })
  }

  const complete = function() {
    return handler.update({ objectId }, {
      status: 'succeeded',
      count: {__op: 'Delete'}
    });
  }

  const fail = function(err) {
    if (typeof err === 'string') {
      err = { message: err };
    }
    const update = {
      errorMessage: err,
      status: 'failed'
    }
    return handler.update({ objectId }, update);
  }

  const rval = {
    setInitial,
    setRunning,
    trackSent,
    complete,
    fail
  };

  // define objectId to be dynamic
  Object.defineProperty(rval, "objectId", {
    get: () => objectId
  });

  return Object.freeze(rval);
}
